U.S. Burial Flag Info

I recently came into possession of a U.S. burial flag (5 feet tall by 9.5 feet long, 100% cotton, made by Valley Forge Flag co.). The flag came with what was called a "sleeve".

The sleeve is basically a 9 foot long tube, made of linen, closed at one end by a drawstring, while the other end is open with a 6 inch diameter opening.

I would like to know the purpose of the sleeve. Was it used in shipping the flag to it's final destination, or was it meant for future storage? The only way I could see it being used would be to roll up the flag lengthwise and then stick it in the tube, but that would leave 6 inches of the flag extending out from the sleeve (which doesn't make sense).